When Right Is on the Left (and Vice Versa): A Case Series of Glioma Patients with Reversed Lateralization of Cognitive Functions.

We report a case series of four patients operated on for a glioma in awake conditions and in whom task-based functional magnetic resonance imaging (fMRI) demonstrated right-dominant activity during a language production task. Language functional sites were identified intraoperatively by electrical stimulations only in the patient with a right-sided lesion. Furthermore, the pre- or postoperative cognitive evaluations in the three patients operated on for a left-sided glioma revealed right spatial neglect and dysexecutive syndrome, hence demonstrating that, in patients with right-dominant activity on language fMRI, the left hemisphere is implicated in spatial consciousness and cognitive control. This study supports the interest of presurgical task-based language fMRI to identify patients with a reversed lateralization of cognitive functions and to make an adequate selection of the battery of intraoperative cognitive tasks to be monitored in those rare outliers.